Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Elements of the barcode locally modify the reflectivity of surfaces on which the barcode is printed. Barcode scanners typically monitor relative intensities of light reflected from different areas of the printed surface, i.e., between areas of the printed surface that are printed with the elements of the barcode and adjoining areas of the printed surface in between the printed barcode elements, such that the patterns of relative intensities monitored by the barcode scanners can be interpreted for decoding the barcode. The barcode patterns can be printed as positive or negative images symbolic of numeric or alphanumeric data.
Typically, the barcode scanners emit beams of light from light sources, such as laser diodes, and measure the intensity of the reflected light, which is typically diffuse, with sensors, such as photo diodes. Optics can be used together with the sensors for capturing more of the reflected light. The light beams can be moved manually, such as in pen-type scanners, or automatically, such as in laser scanners. Variations in the reflectivity of the surfaces across the barcode patterns can be represented by voltage output patterns of the photodiodes, such as waveforms with peaks and valleys corresponding to the different amounts of light returned from the surface areas printed with barcode elements and the adjoining surface areas between the barcode elements. The waveforms can be decoded by pattern recognition software (processed within or in association with the scanner) for returning numeric or alphanumeric values.